Surface-Regulated Low-Temperature Ordering of Pt-Based Intermetallics via Molecular Adsorption–Migration

Platinum-based intermetallic catalysts generally require annealing above 700 °C to establish long-range atomic ordering. Although effective, such high temperatures often induce particle sintering, leading to the reduced dispersion and inefficient utilization of noble metals. In this work, L10 ordering was achieved at a comparatively lower temperature of 550 °C through the introduction of phenol during thermal treatment. Phenol adsorbs on the surface of initially disordered PtM nanoparticles, and the electron-donating character of its hydroxyl group modifies the local surface electronic structure. This interaction appears to facilitate Pt atom diffusion within the intermediate temperature range of 250–350 °C, where atomic rearrangement toward the ordered phase can occur while extensive grain growth remains limited. Electrochemical evaluation shows that the ordered O-PtCo catalyst exhibits improved oxygen reduction activity relative to the disordered counterpart. After 10,000 accelerated durability cycles, the half-wave potential decreases by 5 mV, and approximately 86% of the initial mass activity is retained, suggesting that the ordered framework remains largely preserved. These results indicate that regulating surface adsorption during the intermediate diffusion stage can lower the thermal requirement for ordering and may provide a feasible approach for preparing structurally stable and resource-efficient Pt-based intermetallic electrocatalysts.